Whole body vibration is a new exercise modality with potential applications for training of skeletal muscle as well as bone. There are two different kinds of systems available: so-called low-magnitude vibration (LMV) systems operate with a peak acceleration around 0.3 g, and typically with a vibration frequence of 30Hz, whihlst high-magnitude vibration (HMV) work with frequencies between 15 and 40 Hz, and accelerations of up to 20 g. Dampening by the lower limbs reduce the peak trunk and head accelerations to well below 1 g. Within the HMV systems, greater accelerations can be tolerated when the vibration is side-alternating for both feet. Both systems seen to be safe, with primary concerns mainly being the occurence of lower back pain. However, HMV, applied as an exercise modality rather than ocupationally, even seems to relieve chronic lower back pain(1,2). Many authors believe that muscular contractions are crucial stimuli for adaptive processes in bone. HMV training has been shown to increase muscle power in young men in combination with resistive exercise(3), but not when performed on its own(4). Virtually nothing is knwon about LMV effects upon sekeletal muscle. Evidence suggests that LMV can counteract postmenopausal bone losses at the hip and at the lumbar spine(5), that it can increase bone mineral content in long bone shafts in the leg and in the lumbar spine, both in young osteopenic women(6), as well as in children with cerebral palsy(7). Effects upon bone have also been reported after HMV training for the hip and spine in postmenopausal women(8). However, gains are smal with both LMV and HMVl, and usually not exceeding 2%. This, however, is also the case with other exercise modalities. More impressively that HMV, in combination with resistive exercise has been shown to effectively counteract bone losses from the legs during bed rest, where approximately 1% is lost per month without countermeasure(9). In summary, evidence suggests that, whilst being only of limited value to increase bone strength, both LMV and HMV have good potential to counteract bone losses.Whether this can reduce
© Copyright 2007 12th Annual Congress of the European College of Sport Science, Jyväskylä, Finland - July 11-14th 2007. Alle Rechte vorbehalten.